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Kalkaroo Project (Copper-Gold-Molybdenum) SummaryKalkaroo is a large mineral deposit containing over 100 million tonnes of copper-gold-molybdenum ore that is known to extend for more than 2.5 kilometres along strike and to depths of greater than 200 metres. Its limits have not yet been determined by drilling and there is high potential for discovery of additional ore. Havilah is confident that Kalkaroo will develop into a major new copper mine in South Australia. History of Exploration Kalkaroo was explored by a number of major mining groups in the past including Placer, Newcrest Mining and MIM Exploration, who completed more than 45,000 metres of drilling in the region. Following a detailed evaluation of all historic exploration data, Havilah developed a 3D geological model of an interpreted copper resource envelope which it commenced drill testing in July 2004. This model was not tested by previous explorers.
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Subsequent drilling campaigns expanded the mineralisation to the west, in an area known as West Kalkaroo, where some of the best drilling results were obtained, including 102 metres of 0.83% copper and 1.6 g/t gold in KKRC136. Where Havilah’s drillholes duplicated earlier explorer’s drillholes there was invariably good correlation of assays, providing a high degree of confidence in the drill results. GeologyThe entire region is overlain by a blanket of younger sediments, generally from 30 to 80 metres thick, and averaging about 50 metres at Kalkaroo. Consequently, all information concerning the Kalkaroo deposit is derived entirely from drilling. Kalkaroo mineralisation occurs as two distinct styles. That comprising the large arc or Main Zone, formed as stratabound replacement of a chemically reactive evaporite horizon that dips 45 degrees to the north as a large sheet. This style of mineralisation characteristically contains moderate copper and gold grades and often quite appreciable molybdenum. Drilling indicates that the mineralised horizon is persistent both along strike and down-dip (see section).
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The second style of mineralisation forming the “handle” at West Kalkaroo is hosted by quartz breccias and stockworks developed within a highly fractured, up-faulted footwall block. Copper, and especially gold grades, tend to be significantly higher here, while molybdenum is generally absent. On a regional scale, the Kalkaroo deposit lies on the north-plunging nose of a major structural dome, termed the “south dome”. A second, larger dome known as “north dome” lies to the north. There is enormous regional exploration potential along the prospective horizon in the Kalkaroo north and south domes, as shown by exploration drillhole KKRC071 some 3 km south of the Kalkaroo deposit, which contains 63m of 0.41% Cu and 69 metres of 0.67 g/t Au in expected host rocks. These domes are also cut in a number of places by major fault zones which are also likely hosts to West Kalkaroo style quartz breccia mineralisation.
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2006 Scoping StudyAll relevant drilling data generated prior to 2007 was incorporated into a Vulcan 3D block model, that showed the Kalkaroo resource at that time contained 85 million mineable tonnes at a grade of 0.51 g/t gold and 0.45% copper within an optimised open pit modeled to a depth of 230 metres (using a A$20 per tonne ore value cutoff, and using copper, gold and molybdenum prices roughly half current spot prices). More than 60% of the orebody as outlined above comprised relatively high grade oxidised ore, containing abundant native copper and chalcocite mineralisation. This lies above primary sulphide mineralisation, which extends beyond the deepest drillhole to depths of greater than 250 metres. Molybdenum values are high within certain sections of the deposit, including 48 metres of 858 ppm molybdenum in KKRC006 and 119 metres of 402 ppm molybdenum in KKRC018, which potentially adds considerable value to the copper-gold ore.
Native Copper Samples - Click to enlarge
2007 – 2008 Feasibility StudyIn July 2007, Glencore International joined with Havilah to fund a $14 million feasibility study on the Kalkaroo project. Upon completion of the feasibility study, Glencore may elect to arrange project financing for the subsequent mining joint venture in exchange for taking a 14% participating interest and metals offtake. The feasibility study is on track for completion by the end of 2008. Results so far are extremely positive, with generally wide zones of economic grade copper and gold mineralisation intersected, both in the oxidised and primary zones, including:
Metallurgical testing of large diameter core samples carried out at Optimet laboratory in Adelaide has shown that good recoveries of copper, molybdenum and gold can be obtained by standard gravity and flotation treatment methods from both the oxide and sulphide ore types. In particular:
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